Alcatel-Lucent 6850-48 ネットワークガイド
LINK OAM Overview
Configuring EFM (LINK OAM)
page 16-6
OmniSwitch AOS Release 6 Network Configuration Guide
September 2009
LINK OAM Overview
IEEE standard 802.3ah provides support for LINK OAM. The Clause 57 of std. 802.3ah defines the Oper-
ations, Administration, and Maintenance (OAM) sub layer, which provides mechanisms useful for moni-
toring link operation such as remote fault indication and remote loopback control. LINK OAM provides
network operators the ability to monitor the health of the network and quickly determine the location of
failing links or fault conditions.
ations, Administration, and Maintenance (OAM) sub layer, which provides mechanisms useful for moni-
toring link operation such as remote fault indication and remote loopback control. LINK OAM provides
network operators the ability to monitor the health of the network and quickly determine the location of
failing links or fault conditions.
LINK OAM provides an OAMPDU-based mechanism to notify the remote DTE when one direction of a
link is non-operational and therefore data transmission is disabled. The ability to operate a link in a unidi-
rectional mode for diagnostic purposes supports the maintenance objective of failure detection and notifi-
cation.
link is non-operational and therefore data transmission is disabled. The ability to operate a link in a unidi-
rectional mode for diagnostic purposes supports the maintenance objective of failure detection and notifi-
cation.
Example LINK OAM
OAM information is conveyed in slow protocol frames called OAM Protocol Data Units (OAMPDUs).
OAMPDUs contain the appropriate control and status information used to monitor, test and troubleshoot
OAM-enabled links. OAMPDUs traverse a single link, being passed between peer OAM nodes, and as
such, are not forwarded by MAC clients (e.g., bridges or switches). OAM does not include functions such
as station management, bandwidth allocation or provisioning functions.
OAMPDUs contain the appropriate control and status information used to monitor, test and troubleshoot
OAM-enabled links. OAMPDUs traverse a single link, being passed between peer OAM nodes, and as
such, are not forwarded by MAC clients (e.g., bridges or switches). OAM does not include functions such
as station management, bandwidth allocation or provisioning functions.
The mandatory LINK OAM functions include discovery operations (determining if the other end of the
link is OAM capable and what OAM functions it supports), state machine implementation and some criti-
cal event flows. OAM remote loopback can be used for fault localization and link performance testing.
link is OAM capable and what OAM functions it supports), state machine implementation and some criti-
cal event flows. OAM remote loopback can be used for fault localization and link performance testing.
The features of the LINK OAM protocol discussed in this section are:
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Discovery
Discovery is the first phase of the IEEE 802.3ah OAM protocol. During discovery, information about
LINK OAM node’s capabilities, configuration, and identity are exchanged in the form of OAM protocol
data units (OAMPDUs).
LINK OAM node’s capabilities, configuration, and identity are exchanged in the form of OAM protocol
data units (OAMPDUs).
OmniSwitch
CPE
Site B
OmniSwitch
CPE
Site A
Service Provider
IP Network
IP Network
802.3ah LINK OAM
802.3ah LINK OAM